The Super La Nina and the Coming Winter
October 25th, 2010 - by Art Horn
A Super La Nina is developing. Historically these strong La Nina events drop the earth’s average temperature around one degree Fahrenheit and the drop comes quickly. As a result some of the same places that had record heat this summer may suffer through record cold this winter. La Nina is the lesser known colder sister of El Nino. La Nina chills the waters of the tropical Pacific Ocean and in turn cools the entire planet for one to two years or more. This chilling has the potential to bring bone numbing cold to many parts of the world this and the following winter. As a result world energy demand may spike in the next one to two years as much colder weather hits many of the major industrial nations.
This La Nina appears to be special, at least so far. It is well on its way to being the strongest of these events since the Super La Nina of 1955/56. During that powerful La Nina that lasted two years the global average temperature fell nearly one degree Fahrenheit from 1953 to 1956. The Southern Oscillation Index (SOI) measures the air pressure difference between Darwin, Australia and Tahiti. The lower the value of the index the stronger the El Nino typically is. The higher the SOI index the stronger the La Nina. The September SOI value of +25.0 was the highest of any September going back to 1917 when it was +29.7. During that Super La Nina the global temperature fell 1.2 degrees Fahrenheit from 1915 to 1917. The +25.0 September SOI reading is also the highest for any month dating back to the +31.6 value in November of 1973.
The most recent La Nina developed in the spring of 2007 and persisted until the early summer of 2008. The global average temperature fell one degree Fahrenheit in that period of time, equal to all of the warming of the last 100 years! If the trend of this rapidly developing potentially Super La Nina continues an equal or larger temperature drop can be anticipated during the next one to two years. This La Nina is coming on very fast and very strong. Already it is colder than the 6 coldest La Nina’s of the last 60 years when they were at a similar stage of development.
What about the recent heat we’ve all heard about? For the last year the world has been dealing with the warming effects of a strong El Nino. The El Nino warms the ocean waters of the tropical Pacific Ocean and in turn heats the atmosphere. Western Russia melted under a record heat wave this summer after freezing from record cold last winter. Many parts of the southern United States had record heat this summer but shivered under record cold last winter. The persistence of the jetstream to blow in patterns that changed very little for long periods of time contributed to these extremes of temperature. This locked in jetstream wind pattern enhances temperature anomalies by restricting the exchange of air flow from one place to another. What would be hot becomes very hot and what would be cold becomes very cold.
It is common for the jetstream to behave this way when the sun is in the solar minimum such as we have been in for the last three years. We are emerging from the minimum but the sunspot numbers are continuing to be very low. Some solar experts say this next sunspot maximum may be one of the weakest in 200 years. As a result the tendency for the jetstream to blow over parts of the earth with little month to month variability may continue this year. That would result in continued extremes of temperature. The difference would be this time cold areas would be even colder due to the on coming Super La Nina and the falling global temperature it will cause.
The El Nino of the last year pushed the global temperature right back to where it had been in the beginning of 2007. The result has been no net warming or cooling since then. In fact there has been no net warming or cooling since around 2000. Interestingly the amount of carbon dioxide in the atmosphere has risen from 369 parts per million to 387 ppm (parts per million) during this time. That’s an increase of 18 parts per million. This is 6% above the level of 280 parts per million at the start of the industrial revolution around 1850. Despite this significant rise in carbon dioxide since 2000 there has been no “global warming” during this period.
Right now the Pacific Ocean is in the beginning of a thirty year cooler spell called the Pacific Decadal Oscillation. There is a strong, potentially Super La Nina developing. The sun is still quiet with very few sunspots. When these conditions exist the first two months of the cold season (December and January) tend to be cold from Montana to Iowa to Florida up to the Great Lakes and most of New England. In addition temperatures tend to be very cold from central and western Canada to Alaska. China could suffer a bitterly cold December and January if historic temperature patterns are consistent with current conditions. Much of central and western Europe are cold in these situations as well.
The second half of the cold season (February and March) typically experience some changes in the global temperature patterns in these types of winters. For Europe the changes are not good. Bitter cold and snow dominates from western Russia across all of Europe. In other words what starts as a cold winter in central and western Europe depends into a severe winter in February and March across all of Europe. The extreme cold eases in southern China but it deepens in the north and northeastern part of the country. In the United States the cold of December and January in the middle and eastern part of the country reverses to mild weather from Texas to Florida up to the Great Lakes and New England. All of the western US is cold and snowy up to the northern Great Plains. What starts as a mild winter out west turns much colder with large amounts of snow while the east gets a break from the cold.
The current La Nina is coming on stronger than any in decades. The world is demanding more and more energy to fuel growth even in hard economic times. This winter may test the world energy supplier’s ability to provide it. The resulting increase in demand could produce a spike in energy costs. This could bring more hardship to people who are suffering through this long and deep recession. It remains to be seen if this La Nina equals or exceeds the Super La Nina of 1955/56. Right now El Nino’s colder sister is on the fast track to generate more temperature extremes and a very cold winter in some parts of the world.